This invention relates generally to testing equipment and particularly to test equipment that is built within a conventional sonobuoy system for self testing selected ones of the operating parameters of the sonobuoy.
Sonobuoys have long been used in modern times to provide an acoustic monitoring device in the vicinity of sources of underwater acoustic energy so as to provide a remote monitoring of the sources. A sonobuoy package typically contains a device to control the descent of the sonobuoy from an aircraft into the water and a telemetering electronics package which transmits the acoustic signals intercepted by the sonobuoy to the aircraft by means of a radio frequency telemetering link. The electronics package of one sonobuoy type comprises a plurality of hydrophones prearranged about orthogonal axes, a compass, oscillators, phase shifters and modulators which provide input signals to a transmitter which is coupled to an antenna. A few of the critical sonobuoy operational parameters involve the generation of a reference pilot signal, a phase pilot signal, and modulator carrier signals which are in quadrature phase relationship.
Although the state of the art of the design and fabrication of electronics packages have obtained a high order of quality control, individual variations nonetheless exist between individual units with a variety of possible failures occurring within the sonobuoy either during the manufacturing process or initial deployment within the water. In other instances critical signal parameters, although operational, digress outside acceptable operating limits and compromise data integrity which unknowingly is accepted as valid data at the receiving station.
One prior art method of calibrating and checking sonobuoy operation involves the selective injection of a calibration signal into the electronics system. Such a method provides a go or no-go indication of sonobuoy operation but does not specifically point out the subcircuit failure. For these and a variety of other reasons, the need has been felt for a device for sampling a plurality of operational parameters within a sonobuoy system in order to test the parameters within predetermined tolerances for satisfactory performance and for specifically indicating the failure of critical signals generated within the package.